CN85102277A - Carbon fiber wire sectional area and measure apparatus of youngs modulus - Google Patents
Carbon fiber wire sectional area and measure apparatus of youngs modulus Download PDFInfo
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- CN85102277A CN85102277A CN198585102277A CN85102277A CN85102277A CN 85102277 A CN85102277 A CN 85102277A CN 198585102277 A CN198585102277 A CN 198585102277A CN 85102277 A CN85102277 A CN 85102277A CN 85102277 A CN85102277 A CN 85102277A
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- carbon fiber
- sectional area
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- resistance
- electric capacity
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- 229920000049 Carbon (fiber) Polymers 0.000 title claims abstract description 25
- 239000004917 carbon fiber Substances 0.000 title claims abstract description 25
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 title claims abstract description 25
- 238000005259 measurement Methods 0.000 claims abstract description 10
- 230000007246 mechanism Effects 0.000 claims abstract description 6
- 230000005284 excitation Effects 0.000 claims description 11
- 238000013016 damping Methods 0.000 abstract description 3
- 239000000835 fiber Substances 0.000 description 8
- 230000008859 change Effects 0.000 description 5
- 239000000523 sample Substances 0.000 description 5
- 238000010586 diagram Methods 0.000 description 4
- 238000000034 method Methods 0.000 description 4
- 230000005236 sound signal Effects 0.000 description 4
- 230000003321 amplification Effects 0.000 description 3
- 238000003199 nucleic acid amplification method Methods 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- 239000003990 capacitor Substances 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 230000035945 sensitivity Effects 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- 230000003213 activating effect Effects 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 230000000740 bleeding effect Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 238000009342 intercropping Methods 0.000 description 1
- 230000010355 oscillation Effects 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000009774 resonance method Methods 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
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- Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)
- Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)
Abstract
Carbon fiber wire sectional area and measure apparatus of youngs modulus.The present invention relates to a kind of measurement mechanism that is used to measure carbon fiber monofilament cross-sectional area and axial Young modulus.It utilizes string vibration resonance principle, adopt contactless reception vibration signal and amplify, oscillating component places vacuum system, therefore can eliminate air damping, nonlinear vibration and other interference and loss to greatest extent, thereby the measuring accuracy height, be the useful tool of measuring the important mechanics parameter of carbon fiber monofilament.
Description
The present invention relates to a kind of measurement mechanism that is used to measure carbon fiber monofilament cross-sectional area and axial Young modulus.It utilizes the string vibration resonance principle survey cross-sectional area of fiber, the axial compressional vibration of fiber to survey axial Young modulus, adopts noncontact form received signal, judges the resonance situation of tested carbon fiber monofilament with this.
The cross-sectional area of present measurement carbon fiber monofilament method more accurately is to adopt string vibration resonance method, carbon element central laboratory, Shanghai once reported in April, 1978 and is entitled as " carbon fiber filament strength method of testing " literary composition and has introduced this measuring method, and designed measurement mechanism is divided into vibrational excitation system, sample clamping system, receiving system, signal amplifying system four parts in the literary composition.Tested carbon fiber wire is fixed by the upper grip of sample clamping system, lower end system is the weight of m with the quality, receiving transducer directly contacts with filament to receive vibration signal, the sound signal that the vibrational excitation system that is made up of audio signal generator etc. is sent adds to the carbon fiber monofilament through exciting electrode, make the carbon fiber wire starting of oscillation, vibration signal is received, is shown through the signal amplifying system amplification and by oscillograph by the contact probe.Regulate the frequency of audio signal generator, the excitation fiber silk is made fundamental resonance, and measures its fundamental resonance frequency ν
0, then by ν
0, carbon fiber wire density p and length L, just can obtain its sectional area and be according to formula
A=(mg)/(4 ρ L
2v
0 2); Axially Young modulus is E=(4 π
2Lmv
0 2)/(A), owing to when receiving vibration signal, adopt contact, promptly receiving transducer directly contacts with the fibre single thread that is vibrating, do the serious interference that the vibration that makes carbon fiber wire is popped one's head in like this, make wave form distortion, increase the energy loss of vibrational system, thereby brought new error.
Task of the present invention is that a kind of new pick-up unit will be provided, it needn't just directly contact with the carbon fiber wire that is vibrating can receive filametntary vibration signal, judge its resonance state exactly, thereby accurately measure the cross-sectional area and the axial Young modulus of carbon fiber wire.
Task of the present invention is finished in the following manner: at first the contact probe is received and change the capacitance sensing receive mode into.(or between compressional vibration exciting electrode and carbon fibril lower chuck) formed electric capacity is as sensing capacitance between lateral vibration exciting electrode and carbon fiber wire, this electric capacity be connected on output resistance on the carbon fiber chuck and form an arm of electric bridge; And receive the electric capacity of exciting electrode front end and another arm that resistance is formed electric bridge, this two arm is formed a bridge balance system.The output terminal of electric bridge connects a high input impedance differential operational amplifier again.When carbon fiber is excited to show effect forced vibration, the electric capacity of formed capacitor constantly changes between exciting electrode and the carbon fiber wire or between exciting electrode and the lower chuck, its variable quantity is directly proportional with the amplitude of filament vibration, like this because of variation AC signal that is directly proportional with electric capacitance change on superposition on the output load resistance of this electric capacity, because the existence of this alternating current bridge balanced system, intrinsic background AC signal on the pull-up resistor is separated with the AC signal that gets on because of the electric capacitance change superposition, the AC signal of the reflection carbon fiber wire vibration situation that this superposition gets on is shown by display after the high input impedance differential amplifier amplifies again, the size of the electric signal that shows from display like this, just can correspondingly judge filametntary amplitude size, judge filament thus exactly and whether resonate.
Below with reference to accompanying drawing invention is described in further detail.
Fig. 1 is the synoptic diagram of vibrational excitation system, receiving system, alternating current bridge balanced system.
Fig. 2 is a high input impedance differential operational amplifier wiring diagram.
Fig. 3 is the vacuum system synoptic diagram.
With reference to Fig. 1, form a vibrational excitation system by high voltage direct current generator (1), audio signal generator (2), protective condenser (4), lateral vibration exciting electrode (5) and compressional vibration exciting electrode (6). (1) provides Dc bias; (2) provide the interchange excitation voltage; Its frequency is measured by digital frequency meter (3), and frequency-measurement accuracy is 0.1HZ; (4) capacitance can with 0.1 μ f, withstand voltage be 500 volts, it shields in this device, when (5) and filament (12) when accidentally colliding, it can prevent that high direct voltage from directly scurrying into amplifier.
Dc bias with exchange the excitation voltage effect under, (5) excite (2) to do the lateral vibration of string to measure filametntary cross-sectional area; (6) excite (12) to do compressional vibration to measure filametntary axial Young's modulus. The measuring sequence of these two amounts is by rotary switc S1Carry out.
Calculate proof, as Dc bias V0＞＞exchange excitation voltage amplitude VfThe time, the suffered excitation force of filament is:
F＝2KV
0V
fCOSωt
So, V
0And V
fBig more excitation force is big more, and the filament vibration is just strong more.
This device utilizes between (5) and (12) in addition or the variation of the sensing capacitance electric capacity in the filament vibration processes between (6) and the lower chuck (13) comes detection fibers silk vibrational state (electric capacity is (14) between (5) and (12)), has replaced the contact probe to receive with the sensing capacitance receive mode.Two combine into one with receiving sensing device exciting electrode dexterously in the present invention, plays simultaneously with a device and excite and receive double action, and apparatus structure is greatly simplified.
Because the existence of sensing capacitor (14), the AC signal of being come by (2) will be by this electric capacity and through filament and output load resistance (8), and go up intrinsic background AC signal of generation in (8).When (12) vibrate, the electric capacity of this electric capacity is with intercropping varies with cosine at any time, the changes in capacitance amount is directly proportional with the filament amplitude, goes up AC signal that is directly proportional with electric capacitance change (its variable quantity is directly proportional with amplitude) on the superposition because of the variation of this electric capacity in (8) like this.If we can with certain means with the intrinsic background AC signal of (8) with separate because of the AC signal of electric capacitance change superposition, and this superposition input come out, then the size of the vibration of fiber and its amplitude is through exchanging millivoltmeter or oscillograph shows with regard to available after amplifying.
For the useful signal of going up institute's superposition from (8) detects, the present invention has designed one group of alternating current bridge balanced system.Electric bridge one arm is made up of resistance (8) and electric capacity (14); Another arm is made up of with resistance (9) electric capacity (10) or (11), and (8) equate with the resistance of (9), desirable 220K.
Make Dc bias V before the test earlier
0=0, regulating (10) or (11) then, to make the electric potential difference between electric bridge output A, B at 2 be zero, and balance adjustment is in this operation.After the bridge balancing, the fixed background AC signal between A and the B promptly is cancelled.Balancing capacitance when (10) are for the lateral vibration of survey fiber here, (11) are the balancing capacitance when surveying compressional vibration.After the bridge balancing, slowly add Dc bias then, after bias voltage added, bridge balancing can be subjected to slight damage, at this moment needed to regulate (10) or (11) once more and made bridge circuit balance again, and this moment, test can formally begin.
With reference to Fig. 2, in order to suppress the intrinsic background AC signal in the balance bridge circuit, require to use differential amplifier, because the useful signal that fiber vibration produces only is about 2% of background signal, so require differential amplifier that high as far as possible common-mode rejection ratio (CMRR) is arranged, the CMRR of this device is greater than 80db.Three operational amplifiers (21), (22), (29) can be selected the FOO7B integrated circuit for use, and integrated circuit (21), (22) want strictness to select to make its characteristic identical as far as possible, can improve common-mode rejection ratio like this and reduce noise.Desirable 5 μ of electric capacity (20) in addition, 110K can respectively be got in resistance (23), (25), the desirable 1K of resistance (24), 5K can respectively be got in resistance (26), (27), (28), (30).The output terminal of amplifier can connect ac millivoltmeter or oscillograph is observed, when resonance, and milivoltmeter indication maximal value.Filament, activating system, receiving system, balanced system and amplification system all need electric shield ground connection in addition.
Because the external surface area of carbon fiber monofilament is too big, during the filament vibration, air damping is big, make resonance peak too wide, resonant frequency is difficult for judging on the one hand, causes resonant frequency on the low side on the other hand, makes the cross-sectional area that records higher, therefore be necessary oscillating component is added a vacuum system, to improve measuring accuracy.The vacuum system synoptic diagram is with reference to Fig. 3, and in Fig. 3, (31) are general vacuum glass bell jar, and (32) are vacuum base, and (33) are bleeding point, and the vacuum tightness of system is 10
-2More than the holder.
The present invention is owing to adopt contactless reception and amplification, add that vacuum system can eliminate air damping and other interference and loss to greatest extent, resonance peak is narrowed down greatly, measurement sensitivity greatly improves, given full play to the high-precision advantage of resonant method, and owing to improved measurement sensitivity, just might reduce its Dc bias and interchange exciting voltage (Dc bias of this device is below 80 volts as far as possible, exchange exciting voltage below 10 volts) to eliminate the influence of nonlinear vibration, the measuring accuracy of filament cross-sectional area and axial Young modulus is further enhanced.
Claims (3)
1, the measurement mechanism of a kind of carbon fiber monofilament cross-sectional area and axial Young modulus, it is by the vibrational excitation system.Sample clamping system, receiving system, signal amplifying system and vacuum system are formed, and it is characterized in that:
A, vibration signal receive and adopt the capacitance sensing type receiving trap;
B, one group of alternating current bridge balanced system of employing;
C, tested carbon fiber monofilament place a vacuum system.
2, measurement mechanism as claimed in claim 1, it is characterized in that: the capacitance sensing type receiving trap is made up of the electric capacity that is constituted between lateral vibration exciting electrode (5) and carbon fiber wire (12) or compressional vibration exciting electrode (6) and the lower chuck (13), and exciting electrode and capacitance sensing type receiving trap unite two into one.
3, measurement mechanism as claimed in claim 1 or 2, it is characterized in that: an arm of alternating current bridge balanced system is made up of electric capacity (14) and resistance (8), another arm is made up of with resistance (9) electric capacity (10) or (11), and resistance (8) equates desirable 220K with the resistance of (9).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN85102277A CN85102277B (en) | 1985-04-01 | 1985-04-01 | Carbon fibers section area and young's modulus measuring meter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN85102277A CN85102277B (en) | 1985-04-01 | 1985-04-01 | Carbon fibers section area and young's modulus measuring meter |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN85102277A true CN85102277A (en) | 1986-10-08 |
| CN85102277B CN85102277B (en) | 1988-03-30 |
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ID=4792389
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN85102277A Expired CN85102277B (en) | 1985-04-01 | 1985-04-01 | Carbon fibers section area and young's modulus measuring meter |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN85102277B (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1294413C (en) * | 2004-07-19 | 2007-01-10 | 中国科学院物理研究所 | Method for measuring single linear nanometerial Young's modulus |
| CN102818533A (en) * | 2012-07-29 | 2012-12-12 | 昆明醋酸纤维有限公司 | Methods for detecting section shape and radial profile degree of cellulose acetate fibers |
| CN109540945A (en) * | 2018-08-30 | 2019-03-29 | 北京化工大学 | The method of quantitatively characterizing carbon fiber physical structure |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100346152C (en) * | 2004-06-03 | 2007-10-31 | 电子科技大学 | Electrostatic capacitance type apparatus for measuring Young's modulus |
-
1985
- 1985-04-01 CN CN85102277A patent/CN85102277B/en not_active Expired
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1294413C (en) * | 2004-07-19 | 2007-01-10 | 中国科学院物理研究所 | Method for measuring single linear nanometerial Young's modulus |
| CN102818533A (en) * | 2012-07-29 | 2012-12-12 | 昆明醋酸纤维有限公司 | Methods for detecting section shape and radial profile degree of cellulose acetate fibers |
| CN102818533B (en) * | 2012-07-29 | 2014-07-16 | 昆明醋酸纤维有限公司 | Methods for detecting section shape and radial profile degree of cellulose acetate fibers |
| CN109540945A (en) * | 2018-08-30 | 2019-03-29 | 北京化工大学 | The method of quantitatively characterizing carbon fiber physical structure |
Also Published As
| Publication number | Publication date |
|---|---|
| CN85102277B (en) | 1988-03-30 |
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